1. Field of the Invention
This invention relates in general to a method and apparatus for calibrating disk drives, and more particularly, to a method and apparatus for using personalized calibration data to calibrate disk drives.
2. Description of Related Art
Various types of data storage devices have been developed including high capacity devices that have multiple recording surfaces. A conventional magnetic or optical storage device is typically manufactured as three separate assemblies, the medium, the heads and the controller, which are integrated as a single storage device during one of the final steps in the production process.
A conventional medium assembly includes a plurality of double sided disks arranged in a stack on a central spindle typically rotated by a motor. Each side of each disk is usually plated with a magnetically or optically sensitive coating to form a recording surface for information which is organized in sectors spaced along concentric or spiral tracks on each of the recording surfaces.
The head assembly is used for recording and retrieving the information stored in a sector. Generally the head assembly includes at least one read/write head for each of the surfaces. Each head is typically mounted on a positioning arm which is linked to a servo positioning mechanism capable of moving all heads in unison in a generally radial direction over the recording surfaces. Some storage devices may include multiple head assemblies for a single medium assembly.
The controller assembly is used for managing the information flow between the computer system and the medium. A conventional controller assembly may include one or more microprocessors and memories to perform the complex tasks of address translation, head positioning, data transfer, data correction and performance optimization.
During the power-up sequence of a disk drive, a number of parameters are calibrated to enable reading of information from the storage disk. The parameters are conventionally determined by tuning a set of default parameters stored in non-volatile memory to the specific operating environment of the disk drive. The tuned values are maintained in volatile memory and may periodically be updated by the drive""s maintenance operations to reflect changing conditions such as temperature. However, the calibrated values are not permanently stored, and are lost when the power to the drive is turned off.
Although some parameters have previously been stored on the disk itself, all parameters can not solely be stored on the disk because certain parameters are needed by the servo processor during spin up in order for the head to read data from the disk. The need for initial spin up parameters is especially critical with the use of magneto-resistive heads which require accurate adjustment, increasing track densities which require extremely accurate positioning of the head, and other drive elements requiring accurate tuning. With offsets between the read/write elements of MR heads approaching full tracks, reading stored calibration information on the drive and obtaining system data for drive use without having the data during the power-up sequence is difficult. The precise calibration of such elements causes time delays which negatively impact-drive readiness and the overall disk drive performance. Further, different calibrations may be necessary for manufacturing and field environments.
It can be seen that there is a need for an apparatus, method, and/or system that improves disk drive performance by reducing calibration times.
It can also be seen that there is a need for different calibrations being provided quickly for both manufacturing and field environments.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a technique for enhancing calibration speed and performance of a data storage system.
The present invention solves the above-described problems by providing a technique for calibrating a disk drive that uses personalized calibration data/parameter values stored in non-volatile memory to calibrate the disk drive rather than default parameters based, for example, on population averages.
A system in accordance with the principles of the present invention includes a calibration system/circuit which comprises hardware, software, or a combination of both for calibrating a parameter used in the operation of the disk drive. The system also includes volatile storage for temporarily storing a personalized parameter value generated by the calibration circuit. The system further includes non-volatile storage for storing the personalized parameter value for subsequent use in calibrating the disk drive.
An important aspect of the present invention is that the personalized parameter value stored in non-volatile memory can be updated with a subsequent personalized parameter value in response to systems operations changes.
Another aspect of the invention is that the personalized parameter value can be read to a buffer, merged with a control program, and then saved in non-volatile memory for use in subsequent calibrations.
Another aspect of the present invention is that the calibration circuit includes a control means and a sensor.
Another aspect of the present invention is that the personalized parameter value can be stored in RAM of an interface processor while a working copy of the personalized parameter value can be stored in RAM of a servo processor.
Another aspect of the present invention is that a second copy of the personalized parameter value can be saved on the disk associated with the disk drive.
Another aspect of the present invention is that the calibration circuit is on the disk drive.
Another aspect of the present invention is that the calibration system or elements thereof is remote from the disk drive.
Another aspect of the present invention is that a buffer remote from the disk drive is used to merge control program parameters and personalized parameter values.
Another aspect of the present invention is that a buffer on the disk drive is used to merge control program parameters and personalized parameter values.
Still another aspect of the present invention is that the system can be used to calibrate a disk drive having a replacement control card.
Yet another aspect of the present invention is that the system can be used to personalize replacement control cards for a disk drive.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there is illustrated and described specific examples of an apparatus in accordance with the invention.